1. Field of the Invention
The present invention relates to an antenna device.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2000-348957 (Patent Document 1) discloses a zero phase sequence current transformer. The zero phase sequence current transformer includes a core piece, a secondary winding wound on the core piece, and an end joining terminal for binding an end of the secondary winding.
As described in Patent Document 1, the end of the winding wound on the core piece and the like is bound to a binding terminal called the end joining terminal and the like. Hereby, the winding becomes electrically connectable with another electrical component.
However, when the end of the winding wound on the core piece and the like as above is connected by being bound to the binding terminal, a part of the winding may protrude outside a flange portion of the core piece and the like to form a so-called aerial wiring portion.
If the aerial writing portion is formed, in an antenna device used in a keyless entry system of a vehicle, for example, it becomes highly possible that a disconnection of the winding occurs in the aerial wiring portion and its vicinity. Due to a vibration, heat and the like applied to the antenna device, the aerial wiring portion of the winding and its neighboring part becomes easy to hit an edge of the flange portion repeatedly or winding becomes easy to be disconnected.
In order that the disconnection due to formation of the aerial wiring portion in the winding becomes hard to occur, in a conventional antenna device, a part which may become an aerial wiring portion in a winding is folded back and brought into a twisted line structure to enhance strength or an adhesive (processing agent) is applied on the part which may become the aerial wiring portion in the winding, for example. However, in order to form the twisted line structure by folding back the winding, it is necessary to add a complicated work process for forming the twisted line. In order to apply the adhesive (processing agent), it is necessary to add other processes for its application, and for drying and curing. If such processes are performed to each antenna device, a manufacturing cost of the antenna device is raised compared with a manufacturing cost of a general coil element.
In view of the above-described problems in the antenna device, the present inventor makes the following consideration and completed the present invention.
FIG. 10A to FIG. 10D are explanatory views of types of winding methods for windings in conventional antenna devices. A winding component in four types of antenna devices shown in FIG. 10A to FIG. 10D includes a cylindrical shaped winding shaft portion 41 and a pair of flange portions 42 disposed on both ends in a shaft direction of the winding shaft portion 41. A pair of binding terminals 43 are disposed on the flange portion 42 having a disk shape, in a posture to be parallel to each other.
In FIG. 10A, the pair of binding terminals 43 are disposed on the same side of the flange portion 42 in a case that the flange portion 42 is divided suitably into two parts. Usually, as indicated by two dashed lines in FIG. 10A, the pair of binding terminals 43 are disposed at an angle equal to or less than 90 degrees with the winding shaft portion 41 being a reference. While a tension is applied to the winding 44, the winding 44 is first bound to the binding terminal 43 on a starting side in upper left of the drawing, next wound counterclockwise around the binding shaft portion 41, and finally bound to the binding terminal 43 on a finishing side in upper right. In a case of FIG. 10A, a part of the winding 44 (hereinafter, referred to as a lead-out part 45 of the winding 44 on the starting side of the winding 44) between a part bound to the binding terminal 43 on the starting side and a part wound around the winding shaft portion 41 does not become an aerial wiring portion protruding outside the flange portion 42. A part of the winding 44 (hereinafter referred to as a lead-out part 46 of the winding 44 on the finishing side) between the part wound around the winding shaft portion 41 or a part bound to the binding terminal 43 on the finishing side does not become an aerial wiring portion protruding outside the flange portion 42.
In FIG. 10B, the pair of binding terminals 43 are disposed on the same side of the flange portion 42 similarly to FIG. 10A. While a tension is applied to the winding 44, the winding 44 is first bound to the binding terminal 43 on a starting side in upper left of FIG. 10B, next wound clockwise around the winding shaft 41, and finally bound to the binding terminal 43 on a finishing side in upper right. In the case of FIG. 10B, a lead-out part 45 of the winding 44 on a starting side becomes an aerial wiring portion, when the winding shaft portion 41 is large to an extent that the winding shaft portion 41 is upper in the drawing than a base of a projecting part of the binding terminal 43 of the starting side. A lead-out part 46 of the winding 44 on the finishing side mostly becomes an aerial wiring portion.
In FIG. 10C, the pair of binding terminals 43 are disposed on opposite sides of the flange portion 42. More specifically, the pair of binding terminals 43 are disposed on the flange portion 42 at opposite positions in a manner that the winding shaft portion 41 intervenes in a space therebetween. While a tension is applied to the winding 44, the winding 44 is first bound to the binding terminal 43 on a starting side in upper left of FIG. 10C, next wound counterclockwise around the binding shaft portion 41, and finally bound to the binding terminal 43 on a finishing side in lower right of the drawing. In the case of FIG. 10C, a lead-out part 45 of the winding 44 on the starting side does not become an aerial wiring portion. A lead-out part 46 of the winding 44 on the finishing side mostly becomes an aerial wiring portion.
In FIG. 10D, the pair of binding terminals 43 are disposed on opposite sides of the flange portion 42 similarly to FIG. 10C. While a tension is applied to the winding 44, the winding 44 is first bound to the binding terminal 43 on a starting side in upper left of FIG. 10D, next wound clockwise around the winding shaft 41, and finally bound to the binding terminal 43 on a finishing side in lower right of the drawing. In the case of FIG. 10D, a lead-out part 45 of the winding 44 on the starting side becomes an aerial wiring portion, when the winding shaft portion 41 is large to an extent that the winding shaft portion 41 is upper in the drawing than a base of a projecting part of the binding terminal 43 of the starting side. A lead-out part 46 of the winding 44 on the finishing side does not become an aerial wiring portion.
As shown in these four examples of FIG. 10A to FIG. 10D, there is a possibility that an aerial wiring portion protruding outside a flange portion 42 is formed in a winding 44 of a conventional antenna device. In particular, as shown in FIG. 10C and FIG. 10D, when the pair of binding terminals 43 are disposed on the opposite sides of the flange portion 42, the aerial wiring portion is formed in the winding 44 even if a winding direction around the winding shaft portion 41 is clockwise or counterclockwise. In contrast, when the pair of binding terminals 43 are disposed on the same side of the flange portion 42 and when the winding direction is that of FIG. 10A, the aerial wiring portion is not formed. However, in the case of FIG. 10B, the aerial wiring portion is formed. Further, in the cases of FIG. 10A and FIG. 10B, it is required to wind the winding 44 in the direction shown in FIG. 10A in order to prevent an aerial wiring, so that a manufacturing process of an antenna device is restricted. In order that the aerial wiring portion is not formed, the winding direction or a number of turns of the winding 44 is limited. When the pair of binding terminals 43 are disposed as above on the opposite sides of the flange portion 42 in the conventional antenna device, there is a higher possibility of the aerial wiring portion being formed compared with a case that the pair of binding terminals 43 are disposed on the same side on the flange portion 42.
An object of the present invention is to obtain an antenna device in which an aerial wiring portion protruding outside a flange portion is hardly formed in a winding, when the winding is wound on a binding terminal and a winding component.